3 files changed, 20 insertions, 0 deletions
diff --git a/pkg/sentry/vfs/file_description.go b/pkg/sentry/vfs/file_description.go
index eb5dfd7e2..0c42574db 100644
--- a/pkg/sentry/vfs/file_description.go
+++ b/pkg/sentry/vfs/file_description.go
@@ -354,6 +354,10 @@ type FileDescriptionImpl interface {
 	// represented by the FileDescription.
 	StatFS(ctx context.Context) (linux.Statfs, error)
 
+	// Allocate grows file represented by FileDescription to offset + length bytes.
+	// Only mode == 0 is supported currently.
+	Allocate(ctx context.Context, mode, offset, length uint64) error
+
 	// waiter.Waitable methods may be used to poll for I/O events.
 	waiter.Waitable
 
diff --git a/pkg/sentry/vfs/file_description_impl_util.go b/pkg/sentry/vfs/file_description_impl_util.go
index 3fec0d6d6..6b8b4ad49 100644
--- a/pkg/sentry/vfs/file_description_impl_util.go
+++ b/pkg/sentry/vfs/file_description_impl_util.go
@@ -56,6 +56,12 @@ func (FileDescriptionDefaultImpl) StatFS(ctx context.Context) (linux.Statfs, err
 	return linux.Statfs{}, syserror.ENOSYS
 }
 
+// Allocate implements FileDescriptionImpl.Allocate analogously to
+// fallocate called on regular file, directory or FIFO in Linux.
+func (FileDescriptionDefaultImpl) Allocate(ctx context.Context, mode, offset, length uint64) error {
+	return syserror.ENODEV
+}
+
 // Readiness implements waiter.Waitable.Readiness analogously to
 // file_operations::poll == NULL in Linux.
 func (FileDescriptionDefaultImpl) Readiness(mask waiter.EventMask) waiter.EventMask {
@@ -158,6 +164,11 @@ func (FileDescriptionDefaultImpl) Removexattr(ctx context.Context, name string)
 // implementations of non-directory I/O methods that return EISDIR.
 type DirectoryFileDescriptionDefaultImpl struct{}
 
+// Allocate implements DirectoryFileDescriptionDefaultImpl.Allocate.
+func (DirectoryFileDescriptionDefaultImpl) Allocate(ctx context.Context, mode, offset, length uint64) error {
+	return syserror.EISDIR
+}
+
 // PRead implements FileDescriptionImpl.PRead.
 func (DirectoryFileDescriptionDefaultImpl) PRead(ctx context.Context, dst usermem.IOSequence, offset int64, opts ReadOptions) (int64, error) {
 	return 0, syserror.EISDIR
diff --git a/pkg/sentry/vfs/inotify.go b/pkg/sentry/vfs/inotify.go
index 509034531..c2e21ac5f 100644
--- a/pkg/sentry/vfs/inotify.go
+++ b/pkg/sentry/vfs/inotify.go
@@ -148,6 +148,11 @@ func (i *Inotify) Release() {
 	}
 }
 
+// Allocate implements FileDescription.Allocate.
+func (i *Inotify) Allocate(ctx context.Context, mode, offset, length uint64) error {
+	panic("Allocate should not be called on read-only inotify fds")
+}
+
 // EventRegister implements waiter.Waitable.
 func (i *Inotify) EventRegister(e *waiter.Entry, mask waiter.EventMask) {
 	i.queue.EventRegister(e, mask)